By returning '0' instead of 'EAGAIN' when the tests in xs_nospace() failto find evidence of socket congestion, we are making the RPC engine believethat the message was incorrectly sent and so it disconnects the socketinstead of just retrying.

The bug appears to have been introduced by commit5e3771ce2d6a69e10fcc870cdf226d121d868491 (SUNRPC: Ensure that xs_nospacereturn values are propagated).